Thread grinder



4(hatr 30, 1945.

A. F. MARKUS THREAD GRINDER 5 Sheets-Sheet 1 Filed June 29, 1944 6) 8 zm? P. il-

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THREAD GRINDER Filed June- 29, 1944 5 Sheets-Sheet 2 l m@ gm ww o. QQ

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5 Sheets-Sheet 3 QV Y 0t 30, 1945- A. F. MARKUS THREAD GRINDER FiledJune 29, 1944 Oct. 30, 1945. AF, MARKUS Y 2,388,064

THREAD GRINDER Filed June 29, 1944 5sheets-sht 4 TTO m54? Oct. 30, 1945.A* F. MARKUS 2,388,054` I THREAD GRINDER Filed June 29, 1944 5Sheets-Sheet E5" l usf War/Zad -r-ro Ptnmied oct. 3o, 19454 UNITEDSTATES PATENT \oFF1cE '4 2,388,064 THREAD GRINDER August F. Markus,Detroit, Mich., assignor to Ex- Cell-O Corporation, Detroit, Mich., acorporation of Michigan \k Application June 29, 1944, Serial No. 542,719

18 Claims.

The present invention pertains to a n vel machine for performing threadgrinding operations.

Thegeneral aim of the present invention is to provide a thread grinderembodying a novel and simplified combination of elements such asv toadapt it `especially for production in small sizes while stillincorporating various refinements necessary in producing high precisionwork, the resultantsimplication and minimization of size affording notonly a low cost machine suited to the quantity production of highprecision thread ground parts such as are used, for example, inaircraft, but also one which may be operated with facility by women inview of the small mus"- Fig. 2 is an enlarged fragmentary sectional iview taken from front to rear through the machine substantially alongthe line 2-2 in Fig. 1.

Fig. 3 is a longitudinal sectional view taken substantially along theline 3-3 in Fig. 2.

Fig. 4 is an enlarged detail sectional view taken substantially alongthe line 4 4 in Fig. 2.

Fig. 5 is a perspective view of the drive and operating connections forthe work supported head, the latter being indicated partially in phantomby broken lines.

Fig. 6 is a fragmentary detail perspective view of the adjustablesupport for the grinding wheel included in the machine.

Fig. 7 ls a fragmentary front elevation of the work support andunderlying intermediate supscribe in detail the preferred embodiment,but it is to be understood that I do not thereby intend to limit theinvention to the specific form disclosed, but intend to cover allmodifications and alternative constructions falling within the spiritand scope of the invention as expressed in the appended claims.

Referring more particularly to the drawings,

'the invention has been exemplified therein as embodied in a` `threadgrinder especially adapted for speedy production of high precisionthread ground parts. In Fig. 1, the illustrative machine there shownembodies a grinding Iwheel Ill mounted for rotation about an axisextending generally transversely of the machine and adapted to grind awork piece indicated at W in Fig. 3 and received between centers II aridI2 of headstock and tailstock I4 and I5, respectively, incorporated in aworl supporting head designated generally as I6. .Such head I6 isarranged in a manner hereinafter detailed to reciprocate to and fro pastthe grinding wheel I0 and also to pivot or rock toward and away from thelatter about a horizontal axis generally parallelingthewheels axis ofrotation. Reference is made to the axes as being generally" parallelsince provision is made for adjustably skewing the `heel axis slightlyout of exact parallelism with the work axis to accommodate variousdesired helix angles for the threads to be ground. As will appearhereinafter in connection with detailing of the various parts of theexemplary machine shown, provision is made for tilting the work relativetothe grinding wheel by several mechanisms and for various purposes,viz: (l) to effect incremental infeeding of the work for size controland to effect subsequent rapid retraction ofthe work, (2) to effectprogressive motion of the work toward or from the wheel in timedrelation with the work translation for taper grinding, and (3)` toeffect periodic motion of the work toward and from the wheel in timedrelation with the work rotation, or more often in timed relation withboth the work rotation and translation, for use, for example, in reliefgrinding as in backing off" or relieving the teeth of thread cuttingtools beingyground s'uch as taps or thread milling cutters. l,

Turning now to the'matter of the supporting arrangement for the head I6,the same comprises a guide bar of cylindrical exterior shape along whichthe head is adapted to slide while being I guide bar section II-issolid, being flxed lnped- The - I8 is tubular in form and is fixedintermediate its ends within a pedestal bracket 22 projecting upwardlyfrom the machine base. The opposite or outer end of this guide barsection I8 is supported through the medium of a hollow shaft 23 which isjournaled in it and is in turn journaled in a pedestal bracket 24 on themachine base `2I.

The work supporting head I6 itself comprises a main frame casting 25having depending integral feet 26, 21 bored respectively at 28, 29 toreceive corresponding ones of the guide bar sections I8 and I1. The headI6 is thus adapted to slide axially of the aligned guide bars I1 and I8as well as to rock or pivot laterally about their longitudinal axis. Thetailstock I is of conventional form, being adjustable endwise of thehead frame 25 along guide surfaces 30, 3I (Fig. 2) fashioned on thelatter'and adapted to be releasably clamped in position by a clampingfoot 32 operable by a handle 33. The headstock I4, on the other hand,comprises an upstanding wall 34 (Fig. 3) integral with the head frame 25and bored to receive a work supporting spindle 35 that carries thecenter II. An antifriction bearing 36` in a bore 31 supports one end ofthe spindle 35, whereas the intermediate portion of such spindle isjournaled in a second antifriction bearing 38 carried bya tubularextension 39 on a gear housing 40 removably fixed to the wall 34.

As a part of the mechanism for translating the work supporting head I6in a direction axially of its spindle II, a second head 4I is provided(Fig. 3), the same being tiltable on the guide rod I8 with the first ormain head I6 but restrained against a lalmovement with the latter alongthe guide rod Such second head 4I comprises a main frame casting 42having a depending lower leg 43 which is bored to receive 'thecylindrical guide rod or sleeve I8. A block 44 fixed to the lowerportion of the frame 42 is disposed at the side of the supportingpedestal 24 opposite the leg 43 and coacts with the latter to restrainthe head 4I against movement axially of the guide rod I8. In the upperportion of the head frame 42 a sleeve 45 is revolubly journaled and isvopen at its righthand end (as viewed in Fig. 3). The tubular extension39 on the cover plate 4I! of the other or main head I6 is telescopedwithin this open end of the sleeve 45 so thatthe two head frames areslidably connected for tilting movement in unison while still permittingdisplacement of the same relative to each other in a direction axiallyof the guide rod I8.

Axial feed ofthe main work supporting head I6 is accomplished throughthe use of coacting feed screw and nut elements, one of which elementsis xed to the work supporting spindle 35 carried by the head I6 and theother fixed to the companion or non-translating head 4I. Such screw andnut elements are desirably mounted for ready replacement since the leadof the thread on the feed or master screw must match that being groundon the work piece. instance a feed nut 46 isr clamped to the outer endof the supporting sleeve 45 on the head 4I and,l threaded on afeed'screw 41 keyed to the spindle 35. The nut and its supporting sleeveare normally held stationary, except during adjustment rotation of thesame, so that the turning of the feed screw 41 Within the nut 46, 1n-

cident to rotation of the spindle 35,- causes the latter to be movedaxially in timed relation with its rotation. A removable dust guard 48encloses the outer end of the head 4 I.

Rotation of the work spindle 35 and its feed screw. 41 is accomplishedfrom a drive shaft 49 In the present (Fig. 3) disposed concentricallywith the axis of tilting or pivotal motion of the heads I6, 4I so thatthe drive connections will remain undisturbed during all tiltingmovements of the latter. This shaft 49 is journaled 4within the tubularshaft 23 heretofore mentioned and is driven by a worm gear 5I) (Figs. 3and 6) fixed to its outer end and meshed with a worm 5I which is in turnconnected by a pulley 52 and belt 53 with a reversible electric drivemotor 54 fixed to the lower portion of the machine base 2| (Fig. l). Apinion 55 fixed to the drive shaft 49 meshes with a gear 56 carried by ashaft 51 journaled Within the block 44. For the drive connection forrevolving the spindle 35 the shaft 51 has a sliding spline connection 58with a shaft 59 journaled in the main head I6 and carrying a gear 6I).The latter gear meshes with a second gear 6I rigid with a hub sleeve 62keyed to the spindle 35. As is customary in machines of the generalclass here under consideration, provision is desirably made forautomatically reversing the drive, as for example by the reversal of themotor 54 at the end of each traverse of the work past the grinding wheelso that the work will reciprocate to `and fro past the wheel. Sincecontrols for such purpose are well-known, however, ina variety of formsin the art and since they do not enter into the present invention,detailing here is unnecessary.

Provision is desirably made for lead pickupand backlash compensation.For that purpose a worm wheel 63 (Fig. 5) is fashioned on the exteriorof the feed nut supporting sleeve 45 and meshed with a worm 64 carriedon a shaft 65 journaled in the head frame 42. Either rotation or axialmovement of this shaft 65 correspondinglyfturns the sleeve 45 and feednut 46, thereby shifting the work supporting spindle 35 axia1ly.

For feed pickup the shaft 65 may be turned by a handwheel '66 locatedconveniently at the front of the machine (see also Fig. l), whereas'forpurposes of backlash compensation fluid pressure is applied (from asuitable source, not shown) alternatively to opposite ends of a piston61 fixed to the shaft 65 for urging the same in a directionv appropriateto take up backlashfor .the particular direction of rotation selectedfor the spindle 35.

Progressive tilting motion is imparted to the work supporting head I6 intimed relation with its translation,4 for use in grinding tapered workthrough the action of an adjustably inclined cam or taper bar 68 pivotedto this head at 69 and locked in selected positions of angularadjustment, the bar being arranged to ride over an upwardly projectingpin 10 (Figs. 1, 2 and 5), whereas periodic in and out tilting of thehead in timed relation with its rotation, for use in relief grinding, isaccomplished bythe action of a cam 1I (Fig. 5) 'in periodically tiltinga pivoted transverse bar 12 on the outer end of which the pin 18 ismounted (Fig. 5). The cam 1I is of the peripheral type and comprises adisk eccentrically fixed to a shaft 13 journaled in an intermediatesupporting member 14 hereinafter more particularly described, and isdriven in timed relation with the spindle 35 from the shaft 49 through aset of pick-off gears 15, 16, 11 and 18 arranged to remain in meshthroughout the range of tilting movement of the intermediate support 14.The transverse bar 12 is pivoted on this same intermediate support 14for tilting motion about a generally centrally located adjustable pivotpoint.

To afford an adjustable pivotal support fo;` the bar 12 such bar isslotted longitudinally as indicated at 19 (Fig. 4) and a parallel slotis provided at 8| in an upstanding web 80 on the intermediate support14. Such web is recessed as indicated at 8Ia at the ends of, and alongthe rear of, the slot 8| to permit insertion and removal of parts sothat the slot 8| is in effect dened between two opposed ribs included inthe web 80. A bolt 82 passes through these two slots 19, 8| and hastelescoped on it a bushing 83 with an end flange 83a. Tightening of anut 82a threaded on the bolt 82 thus clamps the web 80 between theopposed headof the bolt and flanged end of the bushing 83 to hold'thelatter rigidly -in a selected position of adjustment along the pair ofdepending lees 89 on the latter (see also Fig. 5). Such legs are pivotedto the inner end of links 90, the latter being pivoted at` theiropposite ends on trunnions 9| projecting laterally from a head 92rotatably mounted on the inner end of an axially movable size controlscrew 93.

The screw 93 is threaded within `a piston 94 (Fig. 2) comprised in thefluid operator 88. Such piston is slidable within a cylinder V95 andkeyed at 98 against rotation. The cylinder is, on the other hand, i'lxedin a body bracket 91 mounted Ain a recess in the front of the machinebase 2|, and having a removablecover plate 98 overlying y the same, aswell as an integral face plate 199 at its length of the slot 8|. `Asecond bushing 84 is journaled on the first bushing 83 and is releasablyclamped to the bar 12 by a nut 84a threaded on such second bushing. Tochange the location of the pivot point for the bar 12 both the nuts 82aand 84a are loosened and the bushing and bolt assembly slid along theregistering slots 19, 8|, being retightened at the selected newlocation. Y

In some instances, as for example in grinding a tapered tap, it isnecessary to use both th taper bar 88 and th'e relief control cam-1I forsimultaneously varying the position of the work piece (through tiltingof the head I 6) relative to the grinding wheel. In other instances itmay be desirable to disable either or both the taper bar 68 and the cam1I. To disable the taper bar it is necessary merely to lock it in suchposition that its lower edge is exactly horizontal or, in other words,in zero taper position. On the other hand, to disable the cam 1I, thenut 84a is loosened, the bar 1.2 slid outward until the cam 1I no longercontacts it, and the bar locked in such position by a clamping bolt (notshown) passed through the registering slots 19, 8|. Variation in thetiming of the cam 1| relative to rotations of the work spindle 35 can,of course, be effected at will by substituting appropriately ratioedsets of pick-olf gears 15 to 18 to accommodate the requirements of aparticular work piece.

The intermediate member 14 heretofore reouter end. When pressure fluidis supplied (from a suitable source and control valves, not shown) tothe left end of the cylinder 95, the piston 94 is thrust to theright,rocking the intermediate support-14 and the head I6 outward away fromthe grinding wheel I0 to eiect a separation of work and tool. Similarly,when pressure fluid is supplied to the opposite or right end of thecylinder 95, the piston 94 is thrust to the left,

rocking the intermediate and work supports towheel preparatory tostarting grinding and in ferred to constitutes a tiltable, butnon-translatable, support on which the main head I6 rests. Theintermediate support 14, being non-translatable, is adapted forattachment to it of suitable actuating means on the base, as willhereinafter appear, for tilting or rocking the same. The head I8, beingrestedon the intermediate support 14 beneath it, rocks or tilts with thelatter but is free to slide lengthwise over it. The other head 4|, beingconnected to the main head I6, of

course rocks with the latter. In the present instance the intermediatesupport 14 is a casting of shelf or apron shape extending generallyhorizontally beneath the overhanging head I8 (Figs. 2 and 5) and ispivoted by integral upstanding legs 85, 88 (Figs. 3 and 5) on the guidebar I 1 coaxially with the head I6.

A size control operating mechanism, designated generally as 81 (Figs. 1and 2) and located conveniently at the front of the'machine, is providedfor tilting the intermediate support 14 to shift the work toward thegrinding wheel in reducing the work to a desired size. Tilting of theintermediate support 14 for quick retraction of the work is, on theother hand, accomplished by a uid operator 88 (Fig. 2). Both themechanism 81 and uid operator 88 are connected to therockableintermediate support 14 through a withdrawing the work at thecompletion of the grinding ol` to interrupt the process. On the otherhand, \the coacting operating mechanism 81 is used to effect theprecision controlled, and relatively slow, advances of the work as thegrinding progresses regilsite to bring the diameter of the work down toaccurately determined size.

It is to be observe` that fluid operator 88 does not in any way distu -bthe setting of the operating mechanism 8'I an\d that, on the other hand,the taper and relief controls heretofore described functionautomatically, in whatever manner they may be set to do,contemporaneously with, but without interference with, the size controlmechanism 81.

The size control mechanism for turning the size control screw 93 maytake a variety of forms. In the illustrative arrangement provision ismade for revolving the screw 93 tok,v adjust its axial position eithermanually or by power. As to the manual operating mechanism, a circularindexing plate |00, having an axial hub |0I, is bolted concentrically toa peripheralflange |02 on t-he forward end of a tubular shaft |03 sothat the two are rotatable as a unit. The forward end of the shaftextension of the screw 93 is splined for rotation and relative axialmovement in the tubular shaft |03, the latter being journaled in abushing |04 in the body bracket. An annular dog ring |05 formed in theperiphery with a Tl` slot I 08 is rotatable on the flange |02 andsupports an annular internal ring gear |01. Meshing with the ring gear|01` is a planetary gear l|08 mounted for rotation on a stub shaft |09supported in and between the flangel |02 and the index plate |00 torevolve therewith. A stub shaft I|0 is conned in and extends through thehub |0| of the index plate |00, and a coaxial sun gear fixed to theinner end thereof meshes with the planetary gear |08.

Fixed on the outer end of the stub shaft I|0 is a hand wheel II 2. Agraduated ring I I3 is rigidly secured to the index plate and rotatablyencircles the hand wheel H2. A second graduated ring H4 is rotatablydisposed in a notch in the periphery of the ring H3, and is securedagainst rotation by a key H bolted to a lug H6 on the front of the base2|. The hand wheel H2 is adapted to be adjustably connected to the indexpla'te |00 for rotation therewith, or to be disengaged therefrom forindependent rotation, by means of a retractable spring detent H1. Thedetent is adapted for selective engagement with any one of a series ofuniformly spaced index apertures ||1a (only one of which is shown) indisengaged from the index plate |00, the hand Wheel H2 is manuallyrotatable independently of the dog ring |05 to adjust the feed screw 93for the purpose of rocking the work supporting head I6 into the initialsize setting as determined by the diameter of the work piece W.IRotation of the hand wheel ||2 acts through the sun gear to turn theplanetary gear |08 and cause the latter to roll along the stationaryring gear |01 thereby rotating the terminal shaft |03. The degree ofadjustmentis indicated by cross graduations on the ring |3 against areference point on the adjacent ring H4, and fine graduations on theformer ring againstreference points on the hand wheel |2. y

A ratchet mechanism is provided for rotating the dog ring |05 through apredetermined degree upon each reversal of movement of the worksupporting head I6. The'ratchet mechanism comprises an annular ratchetwheel H8 having external teeth'and is rigidly secured to the dog ring|05 for rotation with it. Rotatable on the outer end of a bushing |04 inposition against the face plate 99 is a ring |20 having pivoted thereona pawl |2| engageable with the ratchet wheel H8 to advance the same uponoscillation of the carrier ring |20. Such ring is notched at |22 toreceive a pin |23 projecting from a piston |24 slidable endWise within acylinder |25 (Fig. 1) integral with the face plate 99. By means ofsuitable controls, not shown since they form no part of the presentinvention but a variety of forms of which are well-known in the art,pressure fluid is admitted to alternate ends of the cylinder |25 tooscillate the piston |24 in timed relation with the reciprocation of thehead I6.

Turning now to the matter of the mounting of the grinding wheel I0 (seeFig. 2), it will be observed that it is journaled in bearings |26a atthe upper end of a generally upstanding bracket |26. On the lower end ofthis same bracket an electric drive motor |21 is carried on a base |28pivoted to the bracket at |29 so that the weight of the motor willretain taut a belt |30 which connects the same to the grinding wheel.

Provision is made for adjusting the grinding wheel I0 longitudinally ofa work piece carried on the work supporting head I8, as well as forskewing the Wheel axis in accordance with the helix angle of the thread'to be ground. For that purpose flat, accurately machined surfaces |3|,|32

are provided in opposed relation on the machine base 2| and bracket |26,respectively, such surfaces being generally vertical but inclinedslightly forward toward the work in this case. A block |33 (see alsoFig. 6) having flat, accurately machined, parallel opposite side facesis sandwiched between the surfaces |3|, |32. This block is releasablysecured to the base 2| by bolts |34 having heads received in T-slots |35extending longitudinally of the surface |3|, the block being accuratelyguided for adjustment movement axially of the work piece (i. e.,longitudinally of the surface |3I) by a key |36. The bracket |26 is, inturn, similarly secured to the block |33 by bolts |31 having headseceived in T-slots |38 (Fig. 6) which are in this instance arcuate.Adjustment movement of the bracket on the block is accurately guided byan arcuate key |39. The key |39 and slots |38 are centered about a linepassing through the axes of the work and grinding wheel. Both lateraland angular adjustment of the grinding wheel l0 can thus be accomplishedreadily and with precision.

From the foregoing it will be perceived that a grinding machine has beenprovided incorporating what is, in a structural sense, quite a simplework support, but which aiords a high degree of versatility of operationin moving such support i quick retraction or approach motion for thework (by the hydraulic operator 88) and progressive adjustable tilt ofthe work support (by the taper bar 68) in timed relation with theworktranslation for cutting tapers as well as in and out tilting of the work(by the cam 1|) in timed relation with its rotation and translation forrelief grinding. Accordingly, the machine is well adapted for grindingthreads on either straight or tapered work pieces and for performingrelief grinding operations such as are required, for example, ingrinding taps. The adjustment and control of these variousinstrumentalities are simple so that rapid manipulation and high speedproduction result.

I claim as my invention:

1. A thread grinding machine having, in combination, a base, arotatively driven grinding wheel mounted on said base, a stationaryguide rigid with said base and presenting a cylindrical exterior guidesurface positioned. with its longitudinal axis substantially parallelingthe axis of rotation of said wheel, a work supporting head and anintermediate support disposed, respectively, above and beiow said guidewith the head resting on the intermediate support, both the head andintermediate support being journaled on said guide to swing about thelatters axis, means restraining said intermediate support againstmovement longitudinally of the guide While leaving the head free toslide therealong, power actuated means for translating said-headlongitudinally of said guide, and means for adjusting the angle of tiltof said intermediate support to adjust correspondingly the displacementof said head with reference to the grinding wheel.

.2. A thread grinding machine havin'g, in com- Ibm-ation, a base, arotatively driven grinding wheel mounted on said base, a stationaryguide rigid with said base and presenting a cylindrical exterior guidesurface positioned with its longitudinal axis substantially parallelingthe axis of nut restrained against rotation, and means ini cluding ascrew threaded in said nut for operatively connecting said size controldevice to said intermediate support for rocking the .latter in responseto rotation ci' said device.

3. A thread grinding machine having, in combination, va base, arotatively driven grinding wheel mountedon the base, a stationary guiderigid with said base and presenting a cylindrical exterior guide surfacepositioned with its longitudinal axis substantially paralleling the axisof rotation of said wheel, a work supporting head having means thereonslidably embracing said guide to Journal the head on the latter for bothtranslatory movement of the head longitudinally of the guide and bodilyrocking motion of the head about the axis o1' the guide toward and fromthe wheel, an intermediate support also journaled on said guide fortilting moyementabout the latter's axis but restrained againstmovementendwise ofthe guide, said intermediate support being positioned beneaththe head with the latter resting on it and slidable therealong, a sizecontrol device rotatively mounted on said base, a cylinder fixed to saidbase and having a piston slidable therein, a screw threaded axiallythrough said piston and connected at one end to said in- `termediatesupport for rocking the latter in response to endwise displacement oflthe screw effected either by shift of the piston under the influence ofpressure fluid applied thereto or by threading'of the screw through thepiston, `and means forming a spline connection between said i.

size control device and said screw.

4. A thread grinding machine having, in combination. a work support,means including an intermediate support beneath said workv supportsustaining the latter with freedom of endwise sliding movement for thework support with reference to the underlying intermediate support,means mounting both said supports for pivotal motion about a commonhorizontal axis extending longitudinally of the same and restraining theintermediate support against longitudinal motion while leaving the worksupport free for y such motion,'.means for adjustably rocking Asaidintermediate support about said axis to thereby a cylindrical exteriorguide surface positioned with its longitudinal axis substantiallyparalleling the axis of rotation of said wheel, a head including a framehaving a headstock and `a tailstock at opposite ends thereof with a worksupporting spindle journaled in said headstock,

and; means includingdepending feet on said stock and tailstock andslidably embracing said guide to journal the head on the lattergforboth' translatory movement of the head longitudinally` of the guide andbodily swinging motion of the head about the axis of the guide towardand from the wheel.

6. A thread grinding machine having, in combination, a base, arotatively driven grinding wheel mounted on the base, a stationary guiderigid with said base and -presenting a cylindrical exterior guidesurface positioned with its longitudinalaxis substantially parallelingthe axis of rotation of said wheel, ahead having a work supportingspindle journaled therein, means on said head slidably embracing saidguide to journal the head on the latter for both translatoryv Y movementof the head longitudinally of the guide and bodily rocking motion of thehead "about lthe axis of the guide toward and from the wheel, a drivemotor on said base, and a drive connection from said motor and includinga rotatable element concentric withsaidguide axisv for both rotatingsaid spindle and translating said Ihead. 7. In a thread grindingmachine, the vcombination of a base having a guide bar rigidly mountedthereon,v first and second heads journaled on said guide for bodilytilting motion thereof about the latters longitudinal axis, meansrestraining said first head against movement axially of the guide bar,the second head being a-grinding wheel positioned alongside said workspindle for engagement with a workpiece carried by said spindle. 'l

8. In a thread grinding machine, the combination of a base having anelongated guide rigidlyv mounted thereon, first and second headsJQllrnaled on said guide for bodily tilting motion thereof about thelatters longitudinal axis, means restraining said first head againstmovement axially of said guide, the second head being slidable axiallyalong said guide relative to the first head, said first head having anopening therein and a feed nut mounted thereon in alignment with saidopening, a rotatable work spindle Journaled in said second head with itsaxis eccentric to but substantially paralleling said guide, said`spindle having a feed` screw fixed thereto and threaded lin said nut, atubular projection rigid guide for bodily tilting vmotion thereof aboutthev latters longitudinal axis, means restraining said first headagainst movement axially of said guide.

frame located respectively beneath said head`lv the second head beingslidable axially along said guide relative to the first head, said firsthead having a sleeve journaled therein with an open end ipresentedtoward said second head, a feed nut fixed to the end of said sleeveremote from -said second head and concentric with said sleeve,

a rotatable work spindle journaled in said second headwith itsaxiseccentric to but substantially paralleling said guide, `said spindlehaving a feed screw fixed thereto/projecting through said sleeve andthreaded in said nut,\a tubular projection rigid with said second headsurrounding said spindle and slidably telescopd within saidsleeVe toretain said heads in coincidence of angular adjustment aboutthe axisof'said guide, power means for rotating said spindle and screw, means ialongside said work spindle for engagement with a. work piece carried bysaid spindle.

10. A thread grinding machine having, in cornfor adjustably turning saidsleeve to control the "lead pick-up, and a grinding wheel positionedtermediate member and arranged to 'contact' the Aopposite end of saidrocker bar for oscillating the latter about its pivot to raise and lowersaid head in accordance with the movement of said rockerv \bar;\annmeans for connecting said cam in driven relationA with said 'power meansfor rotation of the cam in timed relation with\the rotation of saidspindle.\l X, i

\13. Athread grinding machine having, in co bination, abase, a Worksupport having a work supporting spindle thereon, means mounting saidbination, a base, an intermediate support mounted on said base forrocking motion about a horizontal axis, a work support rested on saidintermedi- `ate support for sliding motion relativeto the latl ter in a.direction para'lleling` said axis a d mountedfor pivotal motion aboutthe same h rizontal axis as said intermediate support, a rot tivelydriven grinding wheel mounted on said base alongside said worksupport,means for adjusting the angle of tilt of said intermediate support totilt the work support correspondingly towardor away from the grindingwheel, and means including adjustable engaging elements carried Arespectively by said -intermediate support and said worksuppoit forprogressively tilting the lat- \ter about\said axis relative ,to theintermediate support inthe course of sliding motion of said work supportalong they intermediate support.

11. A thread grinding machine having, in combination, a base, anintermediate,supportmounted on said base for rocking motion bout ahorizontal axis, a head having-.a work su orting i pindle journaledtherein, said head being ested o said intermediate support fo sliding mtion relative to the latter in a directi lparalleling said axis, meansconnecting` said head to said base for tiltsupport about said axis,power means fory rotating said spindle and translating said head intimed relation, a rotatively driven grinding wheel mounted on said basealongside said work support, means for adjusting the angle of tilt ofsaid intermediate support to tilt the head and its work supportingspindle correspondingly toward or away from the grinding wheel, andmeans including a cam driven by said power means for progressivelytilting said head about said axis relative to the intermediate supportin timed relation with the rotation of said spindle.

12. A thread grinding machine having, in combination, a base, anintermediate support mounted on said base for rocking motion about ahorizoning motion of the head with said intermediate tal axis, a headhaving awork vsupporting spindle Journaled therein, said head beingrested on said intermediate support for sliding `motion relative to thelatter in a direction paralleling said axis,

means connecting said head to said base for tiltingr motion of the headwith said intermediate support about said axis, powe,r means forrotating said spindle and translatingsaid head in timed relation, arotatively driven grinding wheel mounted on said base alowgside saidwork support, means for adjusting heangle f tilt oi said work upport onsaid base for rocking motion about a horizontal axis paralleling saidspindle and for t nslation ina direction paralleling such axis, said"base presenting a generally upright planar surface paralleling saidaxis, a grinding wheel disposed alongside'v said `work support inposition `for" the support to rock toward and away ifrom the same, amountinglbracket for said wheel presenting a surface opposed tosaidsurface on the base, a flat block interposed between said opposedsurfaces,an`d means* keying said block for E adjustment of the samealong said surface on the base in a direction parallelin said 'axis aswell as for angular adjustment of thje bracket relative to said blockabout an axis passing between the axis of said grinding wheel and theaxis of said spindle. l 14. Ay thread grinding maehine comprising, incombination, a base, a tool head on said base and` supporting a rotarygrinding wheel, an inter` mediate supporupivotally mounted on said basefor rocking motion transversely of the axis of said wheel, a worksupport pivotally mounted on said base over said intermediate supportfor rocking.

motion transversely "of said axis and for translation e generallylongitudinally of said axis, a work spindle mounted in said worksupport, means for driving said Work spindle and translating said worksupport in positivetim'e'd relation and in all pivotal positions ofsaidiwork support, means on said intermediate supprt for supporting saidwork support, means for rocking sa'd support` "simultaneously as a unit,and means Ior roeking mediate support. y

15. A thread ,grinding machine comprising, inw,

said work support independently of "said interl e combination, a base, atool head on said base` and supporting a/'rotary grin/,ding wheel, anintermediate support pivotally mounted o sai base for rocking motiontransversely of t/ e axis of said wheel, a work support pivotallymounted on said base over said intermediate support for rocking motiontransversely of said axis/ and for translation generally longitudinallyof lsaid axis, a work spindle mounted in said work support, means fordriving said work spindle'and'translating said work'support in positivetimed relation and in all pivotal positions of ,said work support, meanson said intermediate/support for supporting said work support,means-,ifor rocking said supports simultaneously as a unit,andselectively available means for rocking said work intermediatesupport to tilt thehead and its work Support relative t0 Saidintermediate SHDPQT iill j 2,888,064 "timed relationwi'ththe-translation oi said work support.

16. A thread grinding machine comprising, in combination, a base, a toolhead on said base and supporting a rotary grinding wheel, anintermediate support pivotally mounted on said base'ior rocking motiontransversely of the axis of said wheel, a work support pivotally mountedon said 4said work support for oscillating the latter relative to saidintermediate support.

17. A thread grinding machine comprising, in combination, a base, a toolhead on said base and supporting a rotary grinding wheel, anintermediate support pivotally mounted on said base' for rocking motiontransversely ofthe axis of said wheel, a work support pivotally mountedon said base over said intermediate' support for rocking motiontransversely of said axis and for translation generally longitudinallyof said axis,

x a work spindlemounted in said work support, means. for drivingsaidiwork spindle and transbase over said intermediate support forrocking lating said work support in positive timed relation and in allpivotal positions of said work suD- port, means on `said intermediatesupport for supporting said work support, means for rocking said supportsimultaneously as a"'unit, means for progressively tilting said worksupport relative to said :intermediate support in timed relation with-the translation of -said work support, and means driven in timedrelation with the rotation `of said spindle for oscillating said worksupport relative to said intermediate support.

18. A thread grinding machine comprising, in combination, a base, atoolhead on said base and supporting a rotary grinding wheel, anintermediate support pivotally mounted' on said base for rocking motiontransversely of the axis of said wheel, a work support pivotally mountedon said basev over said intermediate support for rocking `motiontransversely of said axis and for translation generally longitudinallyof said axis, a work spindle mounted in said work support, means fordriving said workspindle and translating said work support in positivetimed relation and in all.

pivotal positions of said work support, means on said intermediatesupport for supporting said work support, means operable in timedrelation with the reciprocation of said work support for impartingsuccessive increments of rocking movement to said supportsimultaneouslyas a unit, and means for rocking said work support relative to saidintermediate support.

AUGUST F. MARKU

